Wikipedia:Reference desk/Archives/Science/2012 July 20

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July 20

Do different languages have different IUPAC names?

Well, sorry for asking this silly question, but I would like to know it. I mean are they comparable to scientific binomial nomenclature of living organisms. Vanischenu m^Talk 16:58, 20 July 2012 (UTC)

The naming rules are universal, however the words themselves are translated depending on the language. Please note this paper, PubMed Tombo7791 (talk) 17:13, 20 July 2012 (UTC)

Thank you so much! That link explained everything. (Did you notice that they thanked WMF in it?:) Vanischenum^Talk 04:10, 21 July 2012 (UTC)

Followup question
There is an Italian article with a different IUPAC name. I do not know why they have omitted the numbers. In our (en) article on it, it was me who put (replaced) the IUPAC name (ref from CHEBI).) So check on it would be helpful. Again thank you.Vanischenum^Talk 04:10, 21 July 2012 (UTC)

It is often omitted when there is no other possible arrangement. 1,1,2,2- is the only choice in this formula. (Unless I am missing something.) Rmhermen (talk) 04:53, 21 July 2012 (UTC)

Thank you! But I wonder why CHEBI has put it on to the IUPAC name. Can you please provide me a reliable IUPAC name source? The problem is, now I cannot trust any of those sites. Even PubChem provided me a false info (on a structure). So a reliable site which provides good IUPAC names. I want them to put as refs in articles. Thank you.Vanischenum^Talk 20:33, 21 July 2012 (UTC)

Freezing a liquid evaporating a part of it

Evaporating a liquid it is absorbing heat, but if you have just one liquid can you use it, evaporating a part of it, at a dissipator and freeze the same type of liquid in another closed chamber? Both parts are at the same temperature. OsmanRF34 (talk) 18:00, 20 July 2012 (UTC)

Yes, at different pressures. 75.166.200.250 (talk) 18:12, 20 July 2012 (UTC)

That's essentially how dry ice is made - they compress the CO2, so it becomes liquid, then release the pressure and some of it evaporates cooling the rest until it freezes (they aren't in separate chambers, though). --Tango (talk) 19:10, 20 July 2012 (UTC)

Yes. The difficulty is that, for most materials, the vapor pressure of the solid is very, very low, and the vapor pressure of the liquid falls quickly as you approach the freezing point. This means that evaporative cooling becomes less effective as you get close to freezing. 75.166 points out that you can get around this by manipulating the pressures in the two reservoirs, and Tango's example of dry ice works well because CO2 has substantial vapor pressure in the solid phase. This online Q&A [1] says that you can also freeze water in a single reservoir with a vacuum pump, and here's a video that does it: [2]. I believe it's not terribly efficient because of the low vapor pressure, but it's interesting to see that it can be done. --Amble (talk) 20:27, 20 July 2012 (UTC)

Liquid argon and liquid nitrogen also solidify if you pump on them. DMacks (talk) 07:57, 21 July 2012 (UTC)

Some substances though are impossible to solidify at room temperature with compression alone. Sagittarian Milky Way (talk) 18:26, 21 July 2012 (UTC)

Indeed they do. A video: [3] --Amble (talk) 23:22, 21 July 2012 (UTC)

I think liquid hydrogen and liquid helium is not made that way unlike warmer cryogenics. I don't know enough to tell if it be impossible if you did that many thousands or millions of atmospheres of pressure though. Sagittarian Milky Way (talk) 21:56, 24 July 2012 (UTC)

What would happen if a whale hit a deepwater petroleum pipe?

Maybe this could be figured out with the whale's mass, speed of swimming, tensile properties of the pipe and whale head compressive strength etc.? Generally mechanics and materials science. And what's the biggest species of whale in oil producing regions? (i.e. North Gulf of Mexico, North Sea, Persian Gulf etc.) Sagittarian Milky Way (talk) 18:22, 20 July 2012 (UTC)

A subsea blowout preventer would close the pipe, under ideal conditions. 79.148.233.179 (talk) 18:28, 20 July 2012 (UTC)

If you have access, you can check out this article "Hydrodynamics of a ship/whale collision" [4]. Which covers a lot of the physics involved. "whale collision" returns many hits on google scholar. But none on the first few pages have anything to do with stationary objects. The paper linked above seems to say that ships pose a special challenge for whales, which are normally rather good at avoiding smashing into things. A more realistic risk to pipelines might be large schools of fish, squid, or jellies. SemanticMantis (talk) 18:32, 20 July 2012 (UTC)

Whales are not bottom feeders.--Shantavira|^{feed me} 09:24, 21 July 2012 (UTC)

The risers I think they're called go up to sea level. And at least sperm whales dive very deep. Better not mess with their ability to use sonar, then. Sagittarian Milky Way (talk) 18:11, 21 July 2012 (UTC)

Thermoelectric materials

I was wondering what the best thermoelectric materials (not for measuring temperature, but rather for generating electricity) are that one would find in a normal household, or could easily and fairly inexpensively obtain at local stores? I know that there are far better out there, but I am not so optimistic about finding Bismuth chalcogenides laying around in the back room. The only other thing that I am concerned about is that they can be safely handled by an inexperienced experimenter. Thanks! Falconus^{p t c} 19:32, 20 July 2012 (UTC)

Solid state heat pumps are made from semiconductors. They are usually in modern CCD cameras, laser diodes, microprocessors, and the like, but I think you probably want to take the diodes out of something like a USB beverage cooler. 75.166.200.250 (talk) 22:10, 20 July 2012 (UTC)

Assuming you don't mean specifically manufacturered thermoelectric devices, such as the beer cooler mentioned by 75.166.200.250 (you did say materials), I don't think you will find anything much. A good thermolectric material combines a high barrier voltage with very low thermal conductivity. The Russians in the 1940's and 1950' made an extensive search for such a material - the best they could come up with is Bismuth Telluride, and even that isn't very good. Bismuth Telluride is what is used in beer coolers, but not because it is efficient, but because it means no moving parts and convenient to make in a size really too small for a compressor. There are two possibilities I can think of: Copper oxide (once used to make diodes), which you can easily make at home, and Russian "radio lamp" materials. I think copper oxide will be so poor you will only be able to measure temperature with it, and not generate usefull power. I will post the instructions for making a radio-lamp generator later, if & when I find the reference. Wickwack120.145.176.214 (talk) 01:43, 21 July 2012 (UTC)

Hmmm, alright thanks. I'll try some stuff and see what I can come up with. Falconus^{p t c} 00:45, 22 July 2012 (UTC)

See http://blog.modernmechanix.com/kerosene-lamp-powers-radio/. The radio's (a tube set) power requirements would be 1.5V at 300 mA and 90V at roughly 10 mA. The materials used in the thermocouples are quite ordinary metals, but I haven't found the reference I had in mind yet. Wickwack124.178.45.60 (talk) 15:22, 22 July 2012 (UTC)

What components of cigarettes keep weight down ?

First, I suppose I should ask if cigarette smokers weigh less, on average, than nonsmokers. If so, do we know why ? Is it the nicotine or the tar ? And what's the mechanism ? Is it that it retards the sense of smell, and thus the appetite ? StuRat (talk) 20:44, 20 July 2012 (UTC)

Nicotine is an appetite suppressant, probably because it's a stimulant.

thx1138 (talk) 20:46, 20 July 2012 (UTC)

Nicotine thx1138 (talk) 20:47, 20 July 2012 (UTC)

Thanks, is it ever prescribed as such ? Or is the additive nature of nicotine enough to prevent that use ? StuRat (talk) 21:00, 20 July 2012 (UTC)

I doubt it. There are plenty of other appetite suppressants you could use that don't have the same nasty side effects as nicotine. Appetite suppressants aren't usually prescribed at all, though - they just aren't that effective a way of losing weight (and they all have some kind of nasty side effects). I saw something in the news recently about the FDA approving a new appetite suppressant - it was newsworthy because its so rare. --Tango (talk) 21:20, 20 July 2012 (UTC)

What side effects does nicotine have other than addictiveness ? How are they worse than other appetite suppressant side effects ? StuRat (talk) 22:09, 20 July 2012 (UTC)

"First causing a release of glucose from the liver" ... so a cigarette is a way to access stored energy, instead of having a snack.  Card Zero  (talk) 21:16, 20 July 2012 (UTC)

I just wrote a long response full of unsourced speculation, then tried to find some sources and the first google hit was Cigarette smoking for weight loss (WP:WHAAOE!). It mostly contradicts what I had written, so I'll just leave you with the link! --Tango (talk) 21:20, 20 July 2012 (UTC)

Smoking also suppresses the sense of smell and thus the flavor of food. 75.166.200.250 (talk) 22:03, 20 July 2012 (UTC)

Smokers weigh less because they're lighter. Mitch Ames (talk) 03:20, 21 July 2012 (UTC)

One thing the article doesn't seem to discuss is that people who give up smoking usually put on weight. However, this seems to be (from my own observations) because they replace the habit of putting a cigarette in their mouth by putting food in their mouth, so they often suck sweets or generally eat more snacks. Maybe the idea that smokers are thinner is backwards logic from the observation that giving up smoking makes people put on weight. Richerman (talk) 09:45, 21 July 2012 (UTC)